I decided to give the beam e4 v2 a go. I have the align 450mx motor with the 15T pinion. What mod is the main gear? I was looking at the spare parts listed at amainhobbies and saw they have 15T pinion available.

be carefull with mixing up other brand's motor pinons, the teeth cut might not be the same as the Beam ones, not because of different modules used, but depending on the number of teeth of the main gear, then there is a tooth profile to modify depending on the motor pinion (Addendum / dedundum). If with a Align pinion you experience excessive wear of the main gear, you will then need a Beam one